1. Field of the Invention
The present invention relates to a liquid crystal display module, and in particular to a liquid crystal display module that enhances light utilization.
2. Description of the Related Art
A hand-held electronic device, such as a cellular phone, is usually small and light. A light source, such as a light emitting diode (LED) or tube, for the liquid crystal display module of the hand-held electronic device is generally supported by a thin power and signal circuit board.
Referring to FIG. 1, a conventional liquid crystal display module 1 is sequentially composed of an LCD panel 11, two prisms 12 and 13, a diffuser 14, a light guide plate 15, a frame 16 and a reflector 17. A groove 18 is formed on one side of the frame 16. A first power and signal circuit board 19, with three light emitting diodes 20 disposed thereon, is disposed in the groove 18. A second power and signal circuit board 21 is connected to one side of the LCD panel 11. When the liquid crystal display module 1 is assembled, the second power and signal circuit board 21 covers the first power and signal circuit board 19 and three light emitting diodes 20 disposed thereon. Light from the light emitting diodes 20 is input to the light guide plate 15 and then reflected into the LCD panel 11 by the reflector 17.
Since none of the light emitting diodes 20 is a spot light source, emitting uni-directional light, the light from the light emitting diodes 20 penetrates the second power and signal circuit board 21 or causes irregular bright areas on the LCD panel 11. Hence, light provided by the light emitting diodes 20 is not fully utilized, thereby reducing the performance of the liquid crystal display module 1.
Referring to FIG. 2, another liquid crystal display module 2 is disclosed to overcome the drawbacks of the liquid crystal display module 1. One surface of a black shading tape 22 is attached to the three light emitting diodes 20 disposed on the first power and signal circuit board 19, and the other surface is attached to the second power and signal circuit board 21. Thus, light from the light emitting diodes 20 does not penetrate the second power and signal circuit board 21.
The black shading tape 22, however, cannot effectively promote utilization of light from the light emitting diodes 20. In other words, the black shading tape 22 increases the total thickness of the liquid crystal display module 2 (or reduces the strength of the frame 16 if the construction of the groove 18 is modified). Since the thickness of the liquid crystal display module 2 is increased, use thereof is thereby limited. Additionally, extra processes and assistant tools are needed to attach the black shading tape 22 to the light emitting diodes 20 and second power and signal circuit board 21 during manufacture of the liquid crystal display module 2, thus increasing manufacturing time and cost and reducing productivity. Moreover, after attachment of the black shading tape 22 is complete, uneven areas thereon must be flattened by a roller or heating and pressurizing method, again increasing the manufacturing time of the liquid crystal display module 2 and reducing the lifespan thereof. Further, if the black shading tape 22 is obliquely or incorrectly attached to the light emitting diodes 20 and second power and signal circuit board 21, the black shading tape 22 must be removed and replaced. Due to this, residual glue on the light emitting diodes 20 and second power and signal circuit board 21 must be removed, thus increasing the manufacturing time of the liquid crystal display module 2.
Hence, there is a need to provide an improved liquid crystal display module to overcome the aforementioned problems. Namely, the present liquid crystal display module can effectively enhance light utilization without increasing the total thickness thereof.